With rapid development of the display technology, the touch screen panel has gradually become a part of people's everyday life. At present, the touch screen panel can be divided into Add on Mode Touch Panel, On Cell Touch Panel and In Cell Touch Panel according to composition structure. The In Cell Touch Panel embeds a touch electrode of the touch panel within the liquid crystal display panel, which not only reduces the thickness of the whole module, but also reduces manufacturing cost of the touch panel greatly. Therefore, the In Cell Touch Panel is favored by panel manufacturers. The In-Cell touch scheme generally includes self-capacitive manner and mutual capacitive manner.
For a liquid crystal display panel of an ADS mode, the self-capacitive manner can be described as follows. The metal layer on the liquid crystal display panel that serves as the common electrode is divided into blocks (i.e., electrode blocks). The blocks can be used as touch sensor units. The touch sensor is connected with a driving IC through a particular touch signal line. When a finger touches the liquid crystal display panel, it will cause fluctuation of the capacitance value of the touch sensor at the corresponding position or the voltage value of the divided common electrode. The driving IC can determine the position of the touch point by testing the fluctuation of the capacitance value, thereby implementing the touch function.
At present, there are various design schemes of the touch signal line in the self-capacitance touch products. As shown in FIG. 1, after the common electrode 02 is divided into blocks, a third insulating layer 03 is formed. Then a touch signal line 04 is formed through patterning process. Afterwards, an insulating layer 12 is further deposited. Finally, the touch signal line 04 and the common electrode 02 are bridged by use of a connection line 14 through punching, so as to enable the touch signal line 04 to play the role of an electrode block lead. Generally, the depth of the via hole a is greater than that of the via hole b, so it requires a longer etching time to etch the via hole a. Hence, if the two via holes need to be etched at a time, the relatively shallow via hole b on the touch signal line 04 may be easily over-etched, which may results in damage of the touch signal metal line layer.
In order to achieve a better etching effect, a relatively thin insulating layer needs to be formed between the pixel electrode and the common electrode. Meanwhile, an insulating layer of a certain thickness is maintained on the touch signal metal line. Thus, on the one hand, it can ensure that the insulating layer covers the touch signal metal line better so as to reduce the over-etching risk. On the other hand, the storage capacitance is increased, so as to ensure a better display effect. However, if dry etching is used to etch a large area of insulating layer located outside the touch signal metal line area so as to reduce the thickness thereof, there will be a great difficulty in carrying out the process, and it will be difficult to etch it completely and the uniformity is poor. Hence, a small size of insulating layer residual cannot be formed through normal depositing, exposing and dry etching.